Australian mine to host first of its kind clean energy storage facility

The Angas zinc mine, just outside Adelaide and currently under care and maintenance, is about to become the site of 5 MW advanced compressed air energy storage or A-CAES project which will provide synchronous inertia, load shifting and frequency regulation to the area's electrical grid.

The developer is Toronto-based Hydrostor, a firm that was awarded $9 million in grants to build the facility, which would allow for variable renewable energy resources such as solar and wind to be integrated into Australia’s National Electricity Market.

According to Hydrostor, the project will repurpose Angas’ existing underground mining infrastructure as the A-CAES system’s sub-surface air storage cavern.

In a media brief, company experts explained that the way the technology works is that it uses electricity from the grid to run a compressor, which produces heated compressed air. Heat is then extracted from the air stream and saved inside a thermal store preserving the energy for use later in the cycle.

The compressed air is then stored in a purpose-built underground cavern, which is kept at a constant pressure using hydrostatic heat from a water column. During charging, compressed air displaces water out of the cavern up a water column to a surface reservoir, and during discharge water flows back into the cavern forcing air to the surface under pressure where it is re-heated using the stored heat and then expanded through a turbine to generate electricity on demand.

“Compressed air storage has the potential to provide similar benefits to pumped hydro energy storage, however, it has the added benefits of being flexible with location and topography, such as utilising a cavern already created at a disused mine site,” said Darren Miller, CEO of the Australian Renewable Energy Agency, the institution that provided $6 million for the project.

The Angas zinc deposit, first discovered in 1991 and acquired by local miner Terramin (ASX: TZN) in 1997, is located on the Fleurieu Peninsula in South Australia. It was placed under care and maintenance in late 2013 as a result of a prolonged drop in metal prices and the current economic reserve being depleted.

The processing plant at Angas was decommissioned but Terramin has been maintaining it with the idea of processing there the ore from its Bird-in-Hand gold project, which is located approximately 30 kilometres north of the zinc mine.

According to the miner, if it gets the required regulatory approvals, its team would modify the plant to process gold-bearing material, while also making use of the existing tailings dam.

Based on Terramin’s December 2018 quarterly activities report, the possibility of restarting the processing plant at Angas does not collide with Hydrostor’s work at the site.